DESCRIPTION: The theme of this application is that 13C and 15N NMR, including indirect detection methods, will be used to quantify the rates of glutamate and glutamine release and uptake in the rat brain in vivo. Studies will also be performed under selected conditions which were chosen for possible clinical relevance: hyperammonemia, steroid therapy, and after inhibition of the glutarnate transporter by an antisense oligonucleotide.